This invention relates to pharmaceutical and cosmetic compositions, particularly waterless compositions.
External topical administration is an important route for the administration of drugs in disease treatment. Many groups of drugs, including, for example, antibiotic, anti-fungal, anti-inflammatory, anesthetic, analgesic, anti-allergic, corticosteroid, anti-psoriasis, retinoid, vitamins and anti-proliferative medications are preferably administered in hydrophobic media, namely ointment. However, ointments often form an impermeable barrier, so that metabolic products and excreta from the wounds to which they are applied are not easily removed or drained away. Furthermore, it is difficult for the active drug dissolved in the carrier to pass through the white petrolatum barrier layer into the wound tissue, so the efficacy of the drug is reduced. In addition, ointments and creams often do not create an environment for promoting respiration of the wound tissue and it is not favorable to the normal respiration of the skin. An additional disadvantage of petroleum jelly-based products relates to the greasy feeling left following their topical application onto the skin, mucosal membranes and wounds. A further problem of non aqueous compositions is achieving formulations in which the active agent is stable.
Some active agents are known to be generally unstable or susceptible to isomerisation or to breakdown, resulting in loss of activity and the use of stabilizers, anti oxidants antimicrobials and buffers and the like in aqueous compositions to protect active or cosmetic agents is known. The problems of protecting active pharmaceutical and cosmetic agents in waterless environments, such as polar compositions are multifold and can vary according to the type of waterless environment and the nature of the agent being used. It has been surprisingly found that factors like small levels of acid residues in the raw materials can be significant in influencing agent stability. Similarly, the presence of low levels of metal ions can act to catalyze reactions or breakdown. Likewise, the presence of agents in a waterless environment that results in ionization or leads to oxidation can act to cause reactions or breakdown. There is therefore a need for simple and elegant solutions to stabilize active ingredients in a waterless or substantially environment.
It would be particularly advantageous and there is an unmet need to have a waterless vehicle addative that is suitable for use not merely one type of API but is adaptable for use with one or more API's from a wide range of different types of API's with relatively minimal or minor adjustment.
Foams and, in particular, foam emulsions are complicated systems which do not form under all circumstances. Changes in foam emulsion composition, such as by the addition of active ingredients may destabilize the foam. There is, therefore, a need for a foam composition, which provides desirable properties to the skin and can remain stable whilst accommodating a variety of active ingredients.
Formulations based on oil or ointment, emollients have a number of useful attributes making them suitable candidates for topical pharmaceutical and cosmetic compositions including foamable compositions. They are inherently stable and inert which are clearly desirable characteristics. They are able to moisturize and soften the skin and in appropriate amounts can act as a protective or barrier layer and can form a barrier to water. By appropriate formulation they can act to improve drug delivery to the skin and yet remain resistant to being washed off. On the other hand they are by their nature greasy materials and can be difficult to formulate particularly into a topical foamable composition that can deliver substantially uniform and stable composition or foam that ameliorates or overcomes the look and feel of a greasy material, especially where that composition is waterless or substantially so. It is further a problem to incorporate into such a vehicle pharmaceutically effective amounts of one or more active pharmaceutical ingredients such that they are uniformly present throughout the formulation and are effectively delivered without the use of an alcohol in the formulation.
On one level it is far from simple or obvious to produce waterless foamable compositions that when released produce foams of quality suitable for pharmaceutical or cosmetic application. On a further level having realized a carrier that will produce a waterless foam of quality there is an additional difficulty to be overcome, namely how to adapt the formula and achieve a formulation, which can accept a range of various active pharmaceutical and cosmetic agents such that the composition and active agent are stable and the foam produced remains of quality. Specifically, one of the challenges in preparing such waterless or substantially waterless foamable compositions is ensuring that the active pharmaceutical or therapeutic agent does not react, isomerizes or otherwise break down to any significant extent during is storage and use. Particularly, there remains an unmet need for improved, easy to use, stable and non-irritating foam formulations, with unique therapeutic or beneficial properties containing a stable or stabilized active pharmaceutical or cosmetic agent.
There remains an unmet need for improved, easy to use, stable and non-irritating topical foam formulations containing a stable or stabilized active pharmaceutical or cosmetic agent having a therapeutic or beneficial effect, intended for treatment of dermal and mucosal tissues.